1. Field of the Invention
This invention relates generally to a apparatus for use in wellbores for recovery of hydrocarbons and more particularly to a production string having a remotely controllable inflow control device for controlling the flow of hydrocarbons from production zones into a production tubing.
2. Background of the Art
To produce hydrocarbons from wellbores, perforations are made through production zones or zones of interest. In cased hole applications, a wellbore casing is placed in the wellbore and the annulus between the casing and the wellbore is filled with a concrete slurry. Perforations are then made through the casing and the concrete and into the production zones for flowing hydrocarbons (formation fluids) from the production zones into the casing. A production string is then placed inside the casing, creating an annulus between the casing and the production string. The fluid from the annulus flows into the production string and is then transported to the surface via a tubing associated with the production string. In open hole applications, the wellbore is typically gravel-packed and a suitable production string is placed in the gravel pack for transporting formation fluids to the surface.
The production string typically includes a sand control device around its outer periphery, which is placed adjacent to each perforated zone to prevent the flow of sand from the production zone into the production string. Sand screens of various designs and slotted liners are commonly used for such purpose. The fluid from the production zone flows through the sand control device and into the production tubing.
The formation fluid resides in the producing formations at a relatively high temperature and at a high pressure. It frequently contains abrasive constituents. The formation fluid, if allowed to pass through the various components of the production string at high flow rates, can quickly erode such components. The velocity of the fluid at which the components start to erode is referred to as the "erosion velocity." The erosion velocity depends upon the type of formation fluid, types of materials used for such components, and the design of such components. A flow control device is typically placed in the production string to create a pressure drop after the formation fluid enters the production string to maintain the fluid flow below the erosion velocity.
Sleeve-type devices have been utilized as flow control devices. Such devices utilize a sleeve placed between the sand screen and the production string interior. In one type of sleeve-type flow control device, to adjust the flow rate through the device, a shifting tool conveyed from the surface, generally by a tubing, is used to move the device between an open position and a closed position. The open position generally defines a fully open valve and the closed position generally defines a position that completely prevents any fluid flow into the production string.
More recently, a sliding sleeve-type device has been proposed that may be set at a selected one of several positions to control the fluid flow rate into the production string. U.S. Pat. No. 5,355,953 discloses such a sleeve-type valve, which is set downhole at one of several positions to control the fluid flow rate. To adjust the flow rate, an external device, such as shifting tool, placed within the production tubing is used to alter the position of the sleeve.
Another type of flow restriction device utilizes a sleeve having a labyrinth for creating a pressure drop before the fluid is allowed to enter the production string interior. The fluid is passed through a predetermined length of a tortuous path before it enters the production string interior. The amount of the pressure drop depends upon the length of the labyrinth through which the fluid must pass. The labyrinth-type devices are preset at the surface before installation in the wellbore. To alter the flow rate, such devices must be retrieved and reset at the surface. This approach can be very expensive, as it requires shutting down the production.
The above-described prior art devices require certain types of intervention to change the flow rate through these devices. Such operations, even if infrequently employed, are expensive and in many cases require shutting down production. It is thus desirable to have a system wherein the fluid flow rate through the production string may be accurately and remotely controlled, without interrupting production operations.
The present invention provides a system wherein the formation fluid leaving the sand screen is passed through an electrically actuated, remotely controllable, adjustable fluid flow control device, which enables adjusting the flow rate to any desired level.